JPH06318785A - Manufacturing method of multilayered-wiring board - Google Patents

Abstract

PURPOSE:To minimize the positional slippage of wiring substrates when a high liquid bonding agent layer is provided between wiring substrates and then the wiring substrates are pressurized to bring wiring patterns into contact with one another for electrically connecting the interlayer parts. CONSTITUTION:A bonding agent layer 6 is formed between wiring substrates 1, 1 having wiring patterns 2 protruded from at least one of the opposite parts requiring of interlayer connection and after making alignment of the wiring patterns requiring of the connection with one another, the bonding agent is locally set for fixing the opposite wiring boards to be thermal pressurized and integrated with one another later.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board.

[0002]

2. Description of the Related Art Since a multilayer wiring board can contain a signal circuit, a power supply, a ground circuit, etc., it is widely used in various electronic devices as an effective method for increasing the wiring density.

As a new method of manufacturing a multilayer printed wiring board,
The inventors of the present invention form an adhesive layer composed of conductive particles and an adhesive having conductivity in a pressing direction between double-sided wiring boards, and laminate the layers by heat and pressure to electrically connect wiring patterns. A method for manufacturing a multilayer wiring board that simultaneously obtains multilayer adhesion has been proposed (see Japanese Patent Application No. 300756 and Japanese Patent Application No. 305942, 1992). In addition, a method has also been proposed in which a similar multilayer wiring board is obtained by directly contacting the wiring patterns to be connected by using an ordinary adhesive having no conductivity in the pressing direction (1992 Patent Application No. 300940). No.).

The characteristics of these methods are that, as in the case of a so-called prepreg made of glass fiber and an adhesive, which is generally used for adhering a circuit board in the manufacture of a multilayer wiring board conventionally used as an adhesive, The point is that a core material that does not flow freely during heating and pressing is not used. The reason why such a core material is not used is that the adhesive between the wiring patterns requiring interlayer connection is eliminated by facilitating the adhesive to flow at the time of lamination and integration by heating and pressurization, and good contact can be obtained to obtain electrical contact. This is to facilitate connection.

[0005]

However, in such a manufacturing method, there is a problem that a positional shift easily occurs between the upper and lower wiring patterns when the layers are integrated by heating and pressing. This is because there is no core material in the adhesive, so that the resistance to the flow of the adhesive melted by heating is small, and the substrate moves with the flow of the adhesive when the layers are integrated by heating and pressing.

The present invention has been made in view of the above problems, and there is little misalignment between upper and lower wiring patterns at the time of stacking and integration, and moreover, a multilayer wiring board capable of reliable interlayer connection even when wiring is thinned. It is an object of the present invention to provide a manufacturing method of.

[0007]

According to the present invention, an adhesive layer 6 is formed between wiring boards 1 and 1 having a wiring pattern 2 in which at least one of facing portions requiring interlayer connection has a wiring pattern 2 protruding from the substrate surface. It is characterized in that the wiring patterns that require connection are aligned, the adhesive is locally cured to fix the opposing wiring boards, and then they are heated and pressed to be integrated.

The structure of the present invention will be described below with reference to the drawings. 1A and 1B are schematic cross-sectional views illustrating an embodiment of the present invention, in which FIG. 1A shows a material configuration, FIG. 1B shows a wiring pattern that requires connection, and an adhesive is locally cured. The completed state is shown, and (c) shows the completed state.

The wiring board 1 is obtained by impregnating a base material such as paper, glass cloth, glass non-woven cloth with a phenol resin, an epoxy resin, a polyimide resin or the like and heating and pressing it, a plastic film such as polyester or polyimide, aluminum or the like. It is made of metal such as iron that has been subjected to insulation treatment, or has a wiring pattern formed on the surface of ceramic or the like. The wiring pattern is formed on both sides of the wiring board 1, but the outermost layer of the multilayer wiring board may be formed on one side.
As for the wiring pattern, it is preferable that both opposing portions that require interlayer connection project from the substrate surface as shown in FIG. However, as long as at least one protrudes from the substrate surface and pressure can be applied during lamination, the other one may have a planar shape or a concave shape.

The protruding portion of the wiring pattern may be a through hole land. These wiring patterns can be formed by a general method such as a tenting method, an additive method, or a transfer method. An adhesive layer may be present between the wiring board 1 and the wiring pattern 2. Further, the connection unnecessary pattern 5 may be present. The surface of the wiring pattern is preferably subjected to a roughening treatment such as mechanical roughening with abrasive grains or chemical roughening with sodium persulfate or the like, because good electrode contact and adhesive force can be obtained.

Next, the adhesive layer 6 will be described. As the adhesive, a curable material that is cured by energy such as heat, light or electron beam is used. Of these, epoxy-based adhesives and imide-based adhesives are preferable because they have excellent adhesiveness and heat resistance due to their molecular structure and can set a wide curing time. The form of the adhesive may be liquid, paste, film or the like. The film-like adhesive is convenient because it has a constant thickness and does not require a coating operation.

The epoxy adhesive is mainly composed of, for example, a high molecular weight epoxy resin, a solid epoxy resin, a liquid epoxy resin, an epoxy resin modified with urethane, polyester, phenoxy, nitrile rubber, etc., and a curing agent and a catalyst,
It is common to add a coupling agent, a filler and the like. Considering electrolytic corrosion resistance, it is desirable that these materials are high-purity products in which Na ⁺ and CI ⁻ of the extracted water are 20 ppm or less.

When conductive particles are contained in the adhesive, the electrical connection becomes more reliable. As a form in which the conductive particles are contained in the adhesive, a dispersion type (1992 Patent Application No. 300
942), a placement type in the main part (Patent application No. 30 of 1992)
No. 5756).

When the adhesive contains conductive particles, the conductive particles include metal particles such as gold, silver, nickel, copper, tungsten, antimony, tin and solder, and carbon particles, which are non-conductive. A polymer core material such as glass, ceramics, plastic, etc., which is formed by coating the above-mentioned conductive layer may be used. Furthermore, insulating coated particles which are formed by coating the above-mentioned conductive particles with an insulating layer and have conductivity in the pressing direction, and the combined use of conductive particles and insulating particles are also very useful for thinning the circuit. It is necessary that the maximum single particle diameter of these conductive particles is smaller than the minimum width of the distance between the adjacent wiring patterns in order to prevent short circuit with the adjacent wiring patterns and to cope with thinning of the wiring. It is preferable that the conductive particles are those which are heated and pressed or deformed by pressing because the contact area with the circuit is increased during lamination and the reliability is improved. Examples of the conductive particles having deformability include coated particles having a conductive layer on the surface of the polymer core material, particles in which the conductive particles form an aggregate and change the aggregate state when pressurized, and low melting point metals such as solder. . Since these particles have deformability due to heating and pressurization during lamination, there are variations in the thickness and flatness of the wiring board and the wiring pattern, or the wiring pattern in which the wiring pattern protrudes from the substrate surface and the wiring pattern that does not protrude. It is easy to handle when mixed.

For the adhesive containing no conductive particles, it is necessary to use a non-conductive core material having a large particle diameter of 5 μm or more, such as glass fiber, in order to obtain good electrical connection. Even when the conductive particles are contained, it is preferable not to use such a core material, and even if it is used, the particle size should be equal to or smaller than the particle diameter of the conductive particles, and the aspect ratio (ratio of major / minor axis).
Should be set to 10 or less.

When the layers are integrated, a wiring board and an adhesive are prepared (see FIG. 1A), and the wiring board has a wiring pattern protruding at least from the board surface. Place the adhesive layer 6 between the substrates 4,
A part of the wiring pattern surface is bonded and fixed while the position of the part requiring connection is adjusted or after the position is adjusted (see FIG. 1B).

As the alignment method, a so-called pin lamination method is used in which through holes are formed in a predetermined number of wiring boards that require lamination and alignment is performed with pins or the like.
There is a method of aligning with the adhesiveness of the adhesive. Upon adhesion and fixing, heat and pressure, electron beam, light, ultrasonic waves, electromagnetic induction, etc. can be adopted, and a method capable of fixing or curing in a short time improves workability and is preferable. Further, the heat resistance of the adhesive after adhesion and fixing needs to be considered so that the heating and pressing in the laminated integration in the next step does not cause a positional deviation.

The adhesive fixing portion 8 has a shape as shown in FIG. (A) is a belt-shaped peripheral portion 7 that is adhesively fixed,
(B) and (c) are those in which the four corners are adhesively fixed, and (d) are those in which a part of the wiring pattern portion 9 is adhesively fixed in a dot shape or a spot shape. In any case, the adhesive layer 6 is formed on the entire surface and a part thereof is fixed. By doing so,
Since the wiring pattern portion 9 and the peripheral portion 7 can be made of the same adhesive material and the adhesive layer 6 can be formed at the same time, the workability is good and the adhesion area is large, which is suitable for preventing the positional displacement.

After the constituent materials are locally adhered and fixed as described above, the whole including the wiring pattern portion 9 is heated and pressed to be laminated and integrated. As an integration method, a general method such as a press or a roll laminator may be used. It is possible to obtain a multilayer wiring board having an arbitrary number of layers by arbitrarily laminating this layer or laminating multilayer wiring boards. The optimum filling amount of the adhesive is controlled by the thickness of the adhesive. After that, the peripheral portion used for adhesive fixing is removed as necessary to obtain a finished product (Fig. 1).
(See (c)).

If necessary, the through holes are filled with a conductive adhesive or plated with through holes to connect all layers to electrical connection.

[0021]

According to the present invention, since the wiring patterns are aligned and a part thereof is adhered and fixed, even if the adhesive melts and flows at the time of heating and pressurizing in the laminated integration of the next step, the upper and lower wiring patterns are mutually connected. It is fixed and does not move.

[0022]

【Example】

Preparation of wiring board A 10 μm thick on both sides of a 50 μm thick polyimide film
A wiring pattern was formed by an etching method on a double-sided substrate bonded with copper foil having a thickness of 18 μm via an adhesive of m. The wiring pattern surface was immersed in an ammonium persulfate aqueous solution (concentration: 100 g / l) for 3 minutes for roughening. The minimum diameter of the wiring pattern that requires connection is 50 μm. The wiring pattern is formed within a 300 mm square, and 1 is formed around the four sides.
It has a portion in which a 5 mm wiring pattern is not formed.

Example 1 Particle size 10 μ having a high molecular weight epoxy resin and a Ni / Au composite conductive layer on the surface of a core material made of crosslinked polystyrene
An adhesive was obtained by mixing 2% by volume of the plated plastic balls of m. This adhesive was applied on a polytetrafluoroethylene film having a thickness of 50 μm so as to have a thickness of 30 μm to obtain an adhesive film. When the adhesive is extracted with pure water at 100 ° C. for 10 hours, Na ⁺ and Cl ⁻ of the extracted water are each 10 ppm or less.

An adhesive film is placed on one of the wiring patterns of the wiring board A which requires connection, and the polytetrafluoroethylene film is peeled off after passing between rubber rolls at 70 ° C., and the other wiring board needs to be connected. The wiring patterns to be aligned are aligned and overlapped. The tack of the adhesive film allowed temporary fixing after alignment.

Next, 4 in which no wiring pattern is formed
The edge part is 180 ° C, 0.5 using a head with a width of 5 mm.
Both wiring boards were fixed by heating and pressing at 30 MPa for 30 seconds to cure the adhesive. Then, the adhesive in the wiring pattern forming portion was cured by heating and pressing at 150 ° C. and 2 MPa for 30 minutes to obtain a multilayer wiring board in which interlayer circuits were electrically connected.

Example 2 An adhesive was obtained by mixing 2% by volume of carbonyl nickel particles having a single particle diameter of 2 μm and an average aggregate particle diameter of 20 μm with a high molecular weight epoxy resin. This adhesive was applied on a polytetrafluoroethylene film having a thickness of 50 μm so as to have a thickness of 30 μm to obtain an adhesive film. Thereafter, a multilayer wiring board was obtained in the same manner as in Example 1.

Example 3 An adhesive was obtained by mixing 2% by volume of insulating coated particles obtained by coating the surface of particles of plated plastic spheres having a particle size of 3 μm with nylon having a thickness of about 0.2 μm in a high molecular weight epoxy resin. This adhesive was applied on a polytetrafluoroethylene film having a thickness of 50 μm so as to have a thickness of 30 μm to obtain an adhesive film. Thereafter, a multilayer wiring board was obtained in the same manner as in Example 1.

Example 4 An adhesive containing a high molecular weight epoxy resin as a main component was applied to a thickness of 50.
A polytetrafluoroethylene film having a thickness of 30 μm was applied onto the film to obtain an adhesive film. Thereafter, a multilayer wiring board was obtained in the same manner as in Example 1.

Comparative Example 1 The same adhesive film as in Example 1 was placed on a wiring pattern of the wiring board A which requires connection, and the polytetrafluoroethylene film was peeled off after passing between 70 ° C. rubber rolls. , Wiring patterns that require connection of other wiring boards were aligned and stacked. The tack of the adhesive film allowed temporary fixing after alignment. In this state, the adhesive in the wiring pattern forming portion was cured by heating and pressing at 150 ° C. and 2 MPa for 30 minutes to obtain a multilayer wiring board in which interlayer circuits were electrically connected.

Example 5 A glass epoxy substrate having a thickness of 0.4 mm was provided with a thickness of 10 on both sides.
A double-sided board was obtained by adhering a copper foil with a thickness of 35 μm through an adhesive of μm. This double-sided board was processed in the same manner as the wiring board A to obtain a wiring board B. The minimum diameter of the wiring pattern requiring connection was 100 μm. Hereinafter, using the adhesive film of Example 1, an interlayer-connected four-layer wiring board was obtained in the same manner as in Example 1.

Comparative Example 2 A wiring board B was laminated and laminated with a 0.2 mm thick glass cloth epoxy resin prepreg (GE-67N, trade name of Hitachi Chemical Co., Ltd.).

The maximum displacement of the upper and lower wiring patterns requiring connection was measured by an X-ray inspection device. Also, the connection resistance at that portion was measured. The results are shown in Table 1.

It can be seen from Table 1 that Examples 1 to 5 all have a small amount of misalignment and have sufficient interlayer connection characteristics. For this reason, the glass transition points of the adhesives of Examples 1 to 5 after curing were 165 ° C. (the adhesive was heated in air at 200 ° C. for 10 minutes, and a viscoelasticity measuring device (Rheospectra DVE-V was used.
4, Rheology Co., Ltd.), tensile mode, 10 Hz, peak temperature of tan δ at 5 ° C./min), and it is considered that the glass transition point of the adhesive is higher than the lamination integration temperature of 150 ° C. To be

In Example 1, the plated plastic balls were appropriately deformed to increase the contact area with the wiring pattern,
In Example 2, the distance between the minimum portions of the opposing wiring patterns was controlled to 2 μm corresponding to the single particle diameter due to the change in the aggregation state, and the number of contacts with the wiring patterns increased. In Example 3, the particles were aggregated due to the small particle size, but conductivity was obtained only in the pressing direction, and the insulating property was maintained even in the portion where the aggregated particle size was larger than the distance between the adjacent wiring patterns.

In Example 4, electrical connection between layers was obtained by direct contact between wiring patterns. In the case of Example 4, formation of irregularities (JIS average roughness 1.8 μm) due to roughening of the pattern surface effectively acted on the contact.

The reason why the conductive particle systems of Examples 1 to 3 described above have a smaller amount of misalignment than that of Example 4 is that the particles act as spacers during heating and pressurization during fixing after alignment, and the adhesive layer having a constant thickness is formed. It is thought that this is due to the formation of

[0037]

[Table 1]

[0038]

As described above, according to the present invention, there is little misalignment between upper and lower wiring patterns at the time of stacking and integration, and a multilayer wiring board using an interlayer connection capable of dealing with wiring thinning is also provided. A manufacturing method can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating an embodiment of the present invention, in which (a) shows a constitution of materials, (b) aligns a wiring pattern requiring connection, and locally cures an adhesive. The completed state is shown, and (c) shows the completed state.

FIG. 2 is a schematic plan view illustrating an example of adhesive fixing relating to the manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 2 Wiring pattern protruding from the board surface 3 First wiring board 4 Second wiring board 5 Connection-free wiring pattern 6 Adhesive layer 7 Peripheral part 8 Adhesive fixing part 9 Wiring pattern part

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Yutaka Yamaguchi 1500 Ogawa, Shimodate, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Haruo Ogino 1500 Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Factory (72) Inventor Yoshiya Nozaki Shimodate City, Ibaraki 1500 Ogawa Oita Hitachi Chemical Co., Ltd. Shimodate Factory

Claims (1)

[Claims] 1. An adhesive layer is formed between wiring boards having a wiring pattern in which at least one of facing portions that require interlayer connection protrudes from the substrate surface, and the wiring patterns that require connection are aligned to form an adhesive. A method for manufacturing a multilayer wiring board, comprising locally curing and fixing opposing wiring boards, and then heating and pressurizing them to integrate them.